The present invention relates to lighting fixtures, and particularly fixtures of the type which utilize an incandescent lamp and are recessed in the ceiling of a room.
Lighting fixtures of this type commonly encounter the problem of excessive heat buildup. While such light fixtures typically include a reflector for directing the majority of the infrared and visible light rays downwardly into the room, nevertheless a considerable amount of heat is transferred upwardly into the recess in which the fixture is mounted. This can subject the wiring of the light fixture to overheating, possibly causing failure of the wiring insulation and resulting in a risk of short circuits and fire. Furthermore, the space above a room ceiling is often filled with thermal insulation to prevent heat loss from the room through the ceiling. Such insulation is frequently formed of flammable material and, therefore, must be kept well away from the recessed lighting fixture to avoid any chance of fire. This clearance space impairs the effectiveness of the insulation.
To avoid the danger of overheating, it has been necessary in many applications that prior recessed lighting fixture arrangements be limited to use with incandescent lamps of no greater than a predetermined maximum wattage, such as 40 watts output so as to minimize the generated heat to an amount insufficient to produce excessive heat buildup. This, of course, also limits the light output.
Another alternative is to provide heat-sensitive switches which automatically disconnect the lamp if the temperature in the fixture rises to a dangerous level. But this can result in annoying and inconvenient interruptions of the light source.